Fabrics can be treated to impart softness, static control and antistatic properties by addition of fabric softening compositions to the rinse cycle, as part of the detergent system, or in the automatic clothes drying cycle of the standard washing and drying routine. Treatment in clothes dryers has been shown to be an effective means for applying softening compositions to textiles. U.S. Pat. No. 3,441,692, to Gaiser, is one of the earlier examples of this softening mode in automatic clothes drying.
Various chemical compositions have been used commercially for softening fabrics when applied during the laundering operation. This softening or conditioning is normally understood and results in a smooth, fluffy feel to the touch. The most common softening compositions include one or more quaternary ammonium salts. Among the most commercially attractive are imadazoline salts, dimethyl dialkyl quaternary salts, and diamidoamine quaternary salts. The majority of these compounds are derived from fatty raw materials, and these cationics have been the subject of many innovations. See, for example, U.S. Pat. Nos. 3,634,947; 3,686,025; 3,095,373; 3,442,692. Disclosures specifically for dryer-added fabric softeners include U.S. Pat. No. 3,676,199. In all of the commercially used dryer-softener systems there is included from 10-30% of a release agent to accomplish the transfer of the active softener to the textile being dried. This requirement for the release agent results in additional handling and manufacturing costs.
We have found that certain salts based on piperazine provide surprisingly good softening and antistatic properties while exhibiting excellent transfer from the dryer sheet to the clothes in the automatic clothes dryer.
It is, therefore, an object of the present invention to provide a material for the treatment of textiles in an automatic dryer to provide softness and static control to the fabric with improved transfer properties from the dryer sheet to the clothes.
It is an additional objective of the present invention to provide a softening system for use in an automatic laundry dryer comprising a softener exhibiting faster biodegradation than currently available systems.
It is an object of the present invention to provide a softening sytem for use in an automatic laundry dryer which requires less or no additive for satisfactory release from the substrate.